Field of the Invention
The present disclosure relates to an image processing circuit and image processing method which are capable of enhancing gray level presentation, and a display device using the same.
Discussion of the Related Art
A dynamic range of images referred to a range of presentable luminance from a dark portion to a bright portion in an input image. High dynamic range (HDR) displays, which have recently come into the spotlight, are capable of displaying an image with very high contrast, deep black and very bright white.
In conventional cases, to implement such HDR display, an average picture level (APL), which is an average of all gray levels of an input image, or a brightness enhancement weight of an image obtained through discrete cosine transform is used to switch a server to widen the dynamic range of the input image.
However, with the average gray level or transformation into the frequency domain alone, perceived brightness characteristics according to gray level distribution may not be reflected, and thus a range narrower than the high dynamic range of human sight may be obtained.
In addition, if the histogram is stretched by applying the APL to the all gray levels for an image having high distribution of high gray levels or/and low gray levels, the middle gray levels are not stretched and thus an inflection point may occur between the middle gray levels and the low gray levels and between the middle gray levels and the high gray levels. These inflection points may result in artifacts in the images.